$$\sqrt{ 4m } = \frac{ { n }^{ 2 } -5 }{ 2 }$$
$m=\frac{\left(5-n^{2}\right)^{2}}{16}$
$-\frac{5-n^{2}}{2}\geq 0$
$n=\sqrt{4\sqrt{m}+5}$
$n=-\sqrt{4\sqrt{m}+5}\text{, }m\geq 0$
